<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="../resct18/react.development.js"></script>
    <script src="../resct18/react-dom.development.js"></script>
    <script src="../resct18/babel.min.js"></script>    
</head>
<body>
    <div id="app"></div>
    <script type="text/babel">
        class App extends React.Component{
            constructor(){
                super()
               this.handle = this.handle.bind(this)
            }
            state={
                cound:0
            }
            render(){
                const {cound}=this.state
                return(
                    <div>
                      <h1>{cound}</h1> 
                      <button onClick={this.handle}>+</button> 
                    </div>
                )
            }
            handle(){
            //在组件中,我们希望事件函数的this指向组件实例,这样可以拿到state等数据
            console.log(this);
            alert(1)
        }
        }
        
    const root= ReactDOM.createRoot(document.getElementById('app'))
    root.render(<App/>)
    </script>
</body>
</html>